Effects of heparin, LMWH, and protamine sulfate infusions on thrombus formation. Thrombus formation after FeCl₃ carotid artery injury preceded by (A) heparin infusion, (B) LMWH (enoxaparin), or (C) protamine sulfate infusion. The thrombosis score is as in Figure 3B. Numbers indicate levels of heparin infusion in which occlusive thrombi occurred at a significantly different rate than in non-heparin-treated mice of that phenotype (P < .05, Student t test; heparin: 1 = mPF4^+/+, 2 = mPF4^+/– [▵], 3 = mPF4^–/– ⋄, and 4 = hPF4⁺ [▪]).